心肺复苏自主循环恢复患者预后影响因素的Logistic回归分析

目的:探讨心肺复苏自主循环恢(ROSC)患者预后影响因素,为临床防治提供参考依据。方法:收集2012年1月-2015年1月在我院行心肺复苏ROSC的148例心脏骤停患者的病历资料,分析患者预后情况,采用Logistic回归方程分析其影响因素。结果:所有患者中,预后良好48例(32.43%),预后不良100例(67.57%)。心脏骤停至复苏开始时间、复苏开始至ROSC时间、复苏后72 h体温、复苏后有无肌阵挛或抽搐、复苏后D-二聚体(D-D)水平、复苏后血pH值、复苏后第3 d急性生理与慢性健康评分(APACHEII)评分均是影响心肺复苏后ROSC者预后的危险因素(P0.05)。结论:影响心肺复苏后ROSC患者预后的因素较多,抢救心脏骤停患者时,应尽可能缩短心肺复苏时间,遵循10 min内抢救原则,有利于改善其预后。     

顺式阿曲库铵在小儿全身麻醉中对气道功能的影响

目的:比较顺式阿曲库铵和阿曲库铵在小儿全麻中对气道功能的影响。方法:选取72名3-9岁患儿,男42例,女30例,采用随机表法将其分为观察组和对照组,每组36例。两组麻醉诱导都采用异丙酚,芬太尼,咪达唑仑。观察组使用顺式阿曲库铵0.15mg/kg,对照组组阿曲库铵0.5 mg/kg,比较两组小儿在插管后5 min、10 min、15 min、20 min患儿P_(ET)CO_2、P-PEAK、听诊呼吸音(粗、细湿啰音)、SPO_2变化四项指标来研究顺式阿曲库铵和阿曲库铵对呼吸系统的影响。结果:观察组注药后5 min、10 min、15 min、20 min时间点P_(ET)CO_2,P-PEAK变化趋势不明显,听诊呼吸音、SPO_2无明显变化(P0.05)。对照组在注药后的4个时间段P_(ET)CO_2、P-PEAK、听诊呼吸音、SPO_2有显著变化,随时间延长,P_(ET)CO_2,P-PEAK有明显增高,SPO_2逐渐下降情况(P0.05)。观察组和对照组相比,5 min、10 min、15 min、20 min各时间点观察组SPO_2高于对照组,PETCO_2、P-PEAK明显低于对照组,啰音发生的概率低于对照组,各时间点各项指标比较差异有统计学意义(P0.05)。结论:顺式阿曲库铵术中对小儿气道功能影响较小,肌松作用理想,可广泛应用于小儿临床麻醉。     

大鼠机械式胸外按压心肺复苏模型的建立

目的探索用机械式胸外按压复制大鼠心肺复苏(cardiopulmonary resuscitation,CPR)模型的可行方法。方法成年雄性SD大鼠,随机分为对照组(n=6)与模型组(n=10)。10%水合氯醛腹腔注射麻醉后行气管插管和左侧股动脉插管。在监测心电图与动脉血压条件下,模型组行气管阻塞(tracheal obstruction,TO),心脏骤停(cardiac arrest,CA)出现2 min用呼吸机辅助和自制动物胸外按压仪行CPR。结果模型组TO后迅速出现自主呼吸停止,紫绀,心律失常,4~5 min出现心脏停搏,动脉收缩压降至40 mm Hg以下,脉压消失,CA出现。2 min后给予CPR,8只大鼠自主循环恢复(return of spontaneous circulation,ROSC),并出现一过性再灌注心律失常,6只大鼠恢复意识并存活24 h。血液生化分析提示模型组大鼠存在电解质紊乱、酸中毒、肾功能损害、心肌酶谱升高。病理学切片观察发现模型组大鼠心肌横纹溶解,肾小球无复流,神经元减少,肺淤血等器官损害。结论机械式胸外按压可以提供CA大鼠CPR所需的基本心输出量,可以成功建立大鼠CPR模型。     

H2S对心跳骤停复苏大鼠脑血流动力学及神经功能的影响

目的:探讨吸入外源性H_2S对心跳骤停复苏大鼠脑血流动力学及神经功能的影响。方法:选择成年雄性SD大鼠18只,随机分为假手术组(sham,n=6)、窒息导致心跳骤停复苏组(CA,n=6)、心跳骤停复苏+H_2S组(H_2S,n=6),观察H_2S对心跳骤停复苏大鼠脑血流的影响。选择成年雄性SD大鼠45只,随机分为sham组(n=5)、CA(n=20)和H_2S组(n=20),观察H_2S对心跳骤停复苏大鼠神经功能和存活率的影响。结果:CA组与H_2S组在ROSC后MAP和CPP均快速上升,远高于基础值(P0.05);而后两组MAP和CPP均缓慢下降,实验结束时,明显低于基础值(P0.05)。两组间比较差异无统计学意义(P0.05)。CA组与H_2S组CBF曲线在ROSC后上升至峰值,随后逐渐下降,两组在峰值无明显差异,但H_2S组CBF减少量显著少于CA组(P0.05)。而在CVR曲线,在实验最后,CA组CVR值仍明显高于基础值(P0.05),而H_2S组基本降至基础值,明显低于CA组(P0.05)。H_2S组的14天存活率(80%)明显高于CA组(50%,P0.05)。在胶带移除实验(tape removal test,TRT)所需时间上,CA组与H_2S组在第1天、第3天及第14天都存在显著差异(P0.05)。H_2S组第14天海马CA1区神经元存活数(33±8)明显多于CA组(20±6,P0.05),但仍较假手术组少(53±10,P0.05)。结论:外源性H_2S吸入对大鼠心跳骤停复苏后MAP及CPP无明显影响。外源性H_2S通过降低CVR,改善CBF,从而改善大鼠心跳骤停复苏后的脑循环。外源性H_2S能明显提高心跳骤停复苏后大鼠的存活率,降低TRT所需时间,同时显著增加海马CA1区神经元的存活,改善大鼠心跳骤停复苏后神经功能转归。     

心肌样细胞移植对大鼠心肌梗死的疗效观察

目的观察心肌样细胞(CLC)移植对心肌梗死大鼠的疗效。方法制备大鼠心肌梗死动物模型,4周后超声检测大鼠血流动力学变化;体外分离、纯化大鼠骨髓间充质干细胞(BMSC),15 ng/ml的胰岛素样生长因子1(IGF-1)诱导BMSC分化为CLC 3,7,14和21 d,采用Western blot技术检测心肌标志性蛋白α-SMA,Ttroponin-T和Troponin-I的表达。CLC移植治疗心肌梗死大鼠,实验共分4组:心肌梗死组,生理盐水对照组,BMSC组及CLC组。移植治疗4周,超声检测血流动力学变化后取材大鼠心肌,冰冻切片,HE染色后检测大鼠心肌梗死的面积。统计分析采用单因素方差分析,实验组之间比较采用t检验。结果心肌梗死模型制备4周,模型组大鼠的LVSP数值为(118.74±11.56)mm Hg,低于假手术组(130.42±12.58)mm Hg,模型组大鼠的LVEDP数值为(14.29±7.63)mm Hg,高于假手术组(2.44±1.11)mm Hg,+dp/dt数值为(2645.17±468.16)mm Hg/s低于假手术组(4087.29±525.17)mm Hg/s,-dp/dt数值为(2487.80±348.21)mm Hg/s低于假手术组(3865.81±614.37)mm Hg/s,差异均具有统计学意义(P0.01)。IGF-1诱导BMSC 3,7,14和21d后均检测到α-SMA、Troponin-T和Troponin-I的表达,与第3天比较P0.01。移植治疗4周后发现生理盐水对照组大鼠血流动力学没有任何改变,BMSC组及CLC组大鼠的LVEDP数值分别为(9.15±4.54)mm Hg和(4.67±3.46)mm Hg,低于心肌梗死组(14.29±7.63)mm Hg,+dp/dt数值分别为(3245.45±368.76)mm Hg/s和(3612.78±468.54)mm Hg/s,高于心肌梗死组(2645.17±468.16)mm Hg/s,-dp/dt数值分别为(3014.11±412.12)mm Hg/s和(3347.21±398.56)mm Hg/s,高于假手术组(2487.80±348.21)mm Hg/s,同时CLC组大鼠的LVEDP(4.67±3.46)mm Hg低于BMSC组(9.15±4.54)mm Hg,±dp/dt数值分别是(3612.78±468.54)mm Hg/s和(3347.21±398.56)mm Hg/s高于BMSC组(3245.45±368.76)mm Hg/s和(3014.11±412.12)mm Hg/s,差异均具有统计学意义(P0.01)。BMSC组和CLC组的心梗面积与心肌梗死组比较明显减小,CLC组的梗死面积与BMSC组比较也明显减小,差异均具有统计学意义(P0.01)。结论 IGF-1诱导BMSC分化为CLC后移植治疗心肌梗死大鼠比单独移植BMSC疗效更好。     

不同低氧时间对SD大鼠颏舌肌肌纤维类型的影响

目的:观察不同低氧时间大鼠颏舌肌肌纤维类型的变化。方法:建立低氧模型,血气分析证实模型成功建立。在低氧不同时间点分别取低氧组和正常组雄性SD大鼠颏舌肌进行HE染色,肌球蛋白ATP酶组织化学染色和RT-PCR检测肌纤维类型的变化。结果:血气分析结果证实低氧组氧分压与血氧饱和度较对照组发生明显下降(P0.05)。低氧1周组、2周组、3周组、4周组较正常组氧分压下降至55.04±2.31 mm Hg,52.69±1.51 mm Hg,49.80±1.39 mm Hg,50.11±3.02 mm Hg(P0.05);血氧饱和度下降至77.51±1.81%,70.13±2.90%,74.20±1.95%,74.97±2.36%(P0.05)。HE染色和肌球蛋白ATP酶组织化学染色法显示低氧2、3、4周组Ⅱ型肌纤维所占比例较相应正常组依次升高:45.92±1.8%,57.44±2.1%,56.89±2.6%,在第三周时达到顶峰(P0.05)。RT-PCR结果也同样验证了这一规律。结论:随着低氧活动的进行,颏舌肌肌纤维类型发生有规律的转化,从而影响着肌肉的功能。     

影响心脏骤停患者心肺复苏成功率的因素分析

目的:分析我院心脏骤停患者心肺复苏的成功率,并探讨其影响因素。方法:选取198名行心肺复苏的心脏骤停患者为研究对象,实施心肺复苏,并记录患者一般情况、复苏开始时间和地点、复苏过程和复苏结局等多项指标,统计分析复苏效果。结果:1198名患者,72例取得最终复苏成功,心肺复苏成功率为36.4%;2不同年龄(=15.380,P0.001)、基础性疾病(x~2=11.465,P=0.043)、复苏开始时间(x~2=57.968,P0.001)、地点(x~2=61.384,P0.001)患者心肺复苏成功率差异有统计学意义,年龄16~60岁、非心血管疾病、心脏骤停5分钟内、院内开始心肺复苏者成功率较高;3复苏成功者和失败者复苏持续时间(t=-5.961,P0.001)和气道建立时间(t=-4.045,P=0.004)的差异具有统计学意义,成功者复苏持续时间要短于失败者,而气道建立时间要早于失败者。结论:快速建立人工气道,不盲目延长心肺复苏时间,提高心脏骤停患者心肺复苏的成功率。     

应用米索前列醇治疗妊高症产后出血的疗效观察

目的:探讨应用米索前列醇对妊高症产后出血的治疗效果。方法:选取我院诊治的200例妊高症产后出血孕妇,将患者分为观察组与对照组,每组100例患者,胎儿娩出后对照组肌注催产素,观察组直肠给予米索丽列醇,按摩子宫,比较治疗后两组患者的平均出血量以及血压状况。结果:治疗前对照组和观察组平均出血量分别为(623.2±45.8)m L、(630.0±46.3)m L(P1=0.176)。治疗后,两组平均出血量分别为(486.1±24.3)m L、(313.3±23.1)m L。与治疗前相比,治疗后两组产妇的出血量均有不同减少,观察组患者少于对照组患者(P2=0.026)。对照组中重度妊高症患者的收缩压及舒张压分别为(170.1±6.7)mm Hg、(113.2±2.1)mm Hg,中度(153.6±5.1)mm Hg、(104.5±5.3)mm Hg,轻度(138.9±4.2)mm Hg、(93.2±2.0)mm Hg。观察组重度妊高症患者中以上指标分别为(169.2±6.5)mm Hg、(114.4±2.5)mm Hg,中度患者(156.2±4.8)mm Hg、(105.9±4.9)mm Hg,轻度患者(140.2±4.4)mm Hg、(90.2±4.4)mm Hg,相应病情下两组患者血压方面均无统计学差异(P3=0.87,P4=0.88,P5=0.75,P6=0.83,P7=0.64,P8=0.92)。对照组和观察组患者中不良反应发生率分别为1.0%(1/100)、2.0%(2/100),差异无统计学意义(P0.05)。结论:米索前列醇直肠用药治疗妊高症产后出血,疗效显著、给药方便、安全性较高,值得进一步推广。     

血液透析血压及其变异性与患者预后的相关性分析

目的:探讨血液透析前后和血液透析过程中血压及其变异性与患者预后的相关性。方法:选取沈阳军区总医院血液透析中心2010年1月1日至2013年12月31日收治的维持性血液透析患者,收集并对比随访期内生存及死亡患者的自然信息及临床资料,评估血液透析过程中患者血压及其变异程度与患者预后的关系。结果:共有269例患者纳入研究,经过4年随访共死亡83(30.86%)例。死亡组年龄显著大于存活组(64.92±13.24岁比49.89±12.86岁,P=0.000),而透析年限显著短于存活组(2.60±2.56年比7.25±4.14年,P=0.000)。死亡组透析前SBP(P=0.001)、DBP(P=0.000)、MAP(P=0.000)均显著高于存活组。两组间透析后SBP、DBP、MAP比较均无显著差异。死亡组△SBP(P=0.026)、△DBP(P=0.001)、△MAP(P=0.001)幅度显著大于存活组。死亡组透析前SBP变异率显著高于存活组(P=0.001);死亡组透析后SBP变异率(P=0.000)、DBP变异率(P=0.014)、MAP变异率(P=0.005)均高于存活组。死亡组每次透析前各时间点间SBP变异率(0.12±0.04 mm Hg比0.09±0.03 mm Hg,P=0.000)与MAP变异率(0.10±0.03mm Hg比0.09±0.03 mm Hg,P=0.001)显著高于非死亡组。结论:维持性血液透析患者透析前血压、透析前后血压改变幅度、透析前后血压变异率、每次透析各时间点间血压变异率等与全因死亡相关。     

不同剂量长托宁联合血液灌流在急性有机磷农药中毒中的应用效果观察

目的:研究不同剂量长托宁联合血液灌流在急性有机磷农药中毒中的应用效果。方法:选取急性有机磷农药中毒患者66例,随机分为A、B两组,每组33例。A组患者给予大剂量长托宁及血液灌流治疗,B组患者给予小剂量长托宁及血液灌流治疗。对比两组临床治疗效果及住院期间不良反应发生情况,对比两组治疗前后实验室指标变化。结果:A组治疗后意识恢复时间、中毒症状消失时间、胆碱酯酶(CHE)恢复时间、住院时间分别为(1.64±0.42)d、(4.84±1.25)d、(4.75±1.21)d、(5.43±1.88)d,显著少于B组的(2.10±0.82)d、(5.22±1.84)d、(5.67±1.92)d、(7.24±2.45)d(P0.05),且A组死亡率0.00%(0/33)显著低于B组的18.18%(6/33)(P0.05)。A组治疗后二氧化碳分压(PaCO2)、肌酸激酶(CK)、肌酸激酶同工酶(CK-MB)水平分别为(38.71±1.44)mm Hg、(74.54±6.12)U/L、(24.45±3.57)U/L,显著低于B组治疗后的(42.43±2.45)mm Hg、(82.78±8.57)U/L、(30.12±5.75)U/L(P0.05),A组治疗后动脉血氧分压(PaO2)水平为(86.91±5.76)mm Hg,显著高于B组治疗后的(83.76±4.87)mm Hg(P0.05)。两组不良反应总发生率(18.18%VS 11.11%)对比无显著差异(P0.05)。结论:与小剂量用药相比,大剂量长托宁联合血液灌流治疗急性有机磷农药中毒疗效更好,且用药安全。     

Unambiguous through-bond sugar-to-base correlations for purines in 13C, 15N-labeled nucleic acids: The HsCsNb,HsCs(N)bCb,and HbNbCb experiments

Summary A set of three 3D (¹H, ¹³C, ¹⁵N) triple-resonance correlation experiments has been designed to provide H1-H8 intraresidue sugar-to-base correlations in purines in an unambiguous and efficient manner. Together, the H_sC_sN_b, H_sC_s(N)_bC_b, and H_bN_bC_b experiments correlate the H1 sugar proton to the H8 proton of the attached base by means of the {H1, C1, N9, C8, H8} heteronuclear scalar coupling network. The assignment strategy presented here allows for unambiguous H1-H8 intraresidue correlations, provided that no two purines have both the same H1 and C1 chemical shifts and the same C8 and N9 chemical shifts. These experiments have yielded H1-H8 intraresidue sugar-to-base correlations for all five guanosines in the [¹³C, ¹⁵N] isotopically labeled RNA duplex r(GGCGCUUGCGUC)₂.     

Short distances between extreme microhabitats do not result in ecotypes in Syntrichia caninervis

Abstract

Phenotypic variation occurs in many populations of plants. When this variation occurs along an environmental gradient, the immediate question is whether the variation is attributed to phenotypic plasticity, ecotypes, or some combination of the two. The moss Syntrichia caninervis appears morphologically variable along an environmental gradient changing rapidly from low light, low temperature, and high moisture levels in the understory microhabitat to high light, high temperature, and low moisture levels in the intershrub microhabitat. We tested for the presence of physiological variation using recovery from a heat-shock event in a mimicked microhabitat light environment, and for morphological variation using a common garden with the ultimate goal of attributing observed variation to plasticity, genetic variation, or a combination. The results suggest that plasticity plays a large role in trait variation. Photosynthetic recovery depended on the current light levels of an environment and not the original microhabitat. The supposed morphological variation in the field was not reflected in the test traits (awn length, leaf area, and shoot volume) and further growth in a common garden continued to show no variation between microhabitats.     

Stereospecific synthesis of new steroidal isoxazoles in dry media

An easy and fast procedure was developed for one-pot synthesis of steroidal isoxazoles starting from 23-acetylsapogenins derivatives in presence of P₂O₅/SiO₂ in dry media under microwaves irradiation is described. Substrates of the 25S and 25R series were used as raw materials, establishing that this new methodology is applicable to both series.     

Altitudinal Changes in Photosynthetic Pathways of Floristic Elements in Southern Sinai, Egypt

High altitude profoundly influenced plant diversity and distribution on mountains of southern Sinai (Egypt). Plants exhibiting the C₃-mode of photosynthesis were widely distributed along the altitudinal transect. Plants exhibiting the C₄-mode were restricted below an altitude of about 1400 m above sea level. The transition from C₃-dominated areas to C₄-dominated areas occurred between 1200 and 1400 m a.s.l. This revised version was published online in August 2006 with corrections to the Cover Date.     

Assessing the Impact of Advected African Dust on Air Quality and Health in the Eastern United States

Large quantities of African dust are carried into the southeastern United States each summer with concentrations typically in the range of 10 to 100?µg m^?3. Because approximately one-third to one-half of the dust mass is in the size range under 2.5?µm diameter, the advection of African dust has implications for the EPA's newly implemented standard for PM_2.5 particulate matter and for the assessment of human health effects. It will be difficult to assess the impact of African dust events on air quality because they occur during the summer (maximum in July) when photochemical pollution events are frequent and intense in the eastern United States. Indeed, the presence of dust could affect the evolution of photochemical dust events. In order to assess the role of African dust in air quality in the United States, it will be necessary to develop a set of diagnostic indicators; it appears that dust mineralogy and elemental composition might be useful for this purpose. Various satellite products can be used to characterize the spatial coverage of dust events and, when coupled with meteorological tools, to predict impact regions.     

Co-function of C3-and C4-photosynthetic pathways in C3, C4 and C3-C4 intermediate Flaveria species

The potential for C₄ photosynthesis was investigated in five C₃-C₄ intermediate species, one C₃ species, and one C₄ species in the genus Flaveria, using ¹⁴CO₂ pulse-¹²CO₂ chase techniques and quantum-yield measurements. All five intermediate species were capable of incorporating ¹⁴CO₂ into the C₄ acids malate and aspartate, following an 8-s pulse. The proportion of ¹⁴C label in these C₄ products ranged from 50–55% to 20–26% in the C₃-C₄ intermediates F. floridana Johnston and F. linearis Lag. respectively. All of the intermediate species incorporated as much, or more, ¹⁴CO₂ into aspartate as into malate. Generally, about 5–15% of the initial label in these species appeared as other organic acids. There was variation in the capacity for C₄ photosynthesis among the intermediate species based on the apparent rate of conversion of ¹⁴C label from the C₄ cycle to the C₃ cycle. In intermediate species such as F. pubescens Rydb., F. ramosissima Klatt., and F. floridana we observed a substantial decrease in label of C₄-cycle products and an increase in percentage label in C₃-cycle products during chase periods with ¹²CO₂, although the rate of change was slower than in the C₄ species, F. palmeri. In these C₃-C₄ intermediates both sucrose and fumarate were predominant products after a 20-min chase period. In the C₃-C₄ intermediates, F. anomala Robinson and f. linearis we observed no significant decrease in the label of C₄-cycle products during a 3-min chase period and a slow turnover during a 20-min chase, indicating a lower level of functional integration between the C₄ and C₃ cycles in these species, relative to the other intermediates. Although F. cronquistii Powell was previously identified as a C₃ species, 7–18% of the initial label was in malate+aspartate. However, only 40–50% of this label was in the C-4 position, indicating C₄-acid formation as secondary products of photosynthesis in F. cronquistii. In 21% O₂, the absorbed quantum yields for CO₂ uptake (in mol CO₂·[mol quanta]^-1) averaged 0.053 in F. cronquistii (C₃), 0.051 in F. trinervia (Spreng.) Mohr (C₄), 0.052 in F. ramosissima (C₃-C₄), 0.051 in F. anomala (C₃-C₄), 0.050 in F. linearis (C₃-C₄), 0.046 in F. floridana (C₃-C₄), and 0.044 in F. pubescens (C₃-C₄). In 2% O₂ an enhancement of the quantum yield was observed in all of the C₃-C₄ intermediate species, ranging from 21% in F. ramosissima to 43% in F. pubescens. In all intermediates the quantum yields in 2% O₂ were intermediate in value to the C₃ and C₄ species, indicating a co-function of the C₃ and C₄ cycles in CO₂ assimilation. The low quantum-yield values for F. pubescens and F. floridana in 21% O₂ presumably reflect an ineffcient transfer of carbon from the C₄ to the C₃ cycle. The response of the quantum yield to four increasing O₂ concentrations (2–35%) showed lower levels of O₂ inhibition in the C₃-C₄ intermediate F. ramosissima, relative to the C₃ species. This indicates that the co-function of the C₃ and C₄ cycles in this intermediate species leads to an increased CO₂ concentration at the site of ribulose-1,5-bisphosphate carboxylase/oxygenase and a concomitant decrease in the competitive inhibition by O₂.Abbreviations PEP phosphoenolpyruvate - PGA 3-phosphoglycerate - RuBP ribulose-1,5-bisphosphate     

Magnesium uptake kinetics in loblolly pine seedlings

Recent studies have suggested that the growth of loblolly pine (Pinus taeda L.) has declined in the southern United States and it has been hypothesized that foliar Mg deficiency may play an important role in the perceived decline. Quantitative nutrient uptake models such as the Barber-Cushman model have been used successfully to investigate nutrient uptake by crop species under a variety of field and experimental conditions and may provide one approach to evaluating this question. However, in order to use this approach it is necessary to develop, for the plant species and nutrient of interest, values for maximal nutrient influx rate at high solution concentrations (I_max), the solution concentration where net influx is 0.5 I_max (K_m), and the nutrient concentration below which influx ceases (C_min). As a first step in evaluating the potential of such an approach, two sets of experiments using established solution nutrient depletion techniques were used to define these values for loblolly pine seedlings 180, 240, 365, and 425 days in age. Observed I_max values for Mg range from 7.90E-8 to 1.29E-7 mol cm^–2 s^–1 with younger seedlings having higher values. Values of K_m for all seedling ages were quite similar ranging from 8.69 to 8.58E-3 mol cm^–3. Most importantly, the results of both experiments indicate that during a growth flush, seedlings will withdraw Mg from solution until the concentration is essentially zero (C_min=0). During non-flush periods uptake rates appear to be greatly reduced. Therefore, efforts to model Mg uptake will need to take these differences as well as seedling age influences into consideration.     

八肽胆囊收缩素对大鼠大脑皮质细胞钙调素活性的影响

为了探讨胆囊收缩素(CCK)受体在中枢神经系统中的信号传递机制,观察了CCK₈和CCK_A受体拮抗剂L-364,718、CCK_B受体拮抗剂L-365,260对大鼠大脑皮质钙调素（CaM）活性的影响.结果表明：a.CCK₈对CaM活性的影响具有时间依赖性,15 min达到最高点后逐渐下降;b.CCK₈在10^－12～10^－7 mol/L范围内可刺激CaM活性的增加,超过10^－7 mol/L后,逐渐趋于饱和.c.CCK_A受体拮抗剂L-364,718、CCK_B受体拮抗剂L-365,260均可抑制10^－7 mol/L CCK₈引起的CaM活性的增加,但两者IC₅₀相差40倍,L-365,260在较低浓度时即能明显拮抗CCK₈引起的CaM活性变化.研究结果提示CCK₈可能通过CCK_B受体引起CaM活性变化,而CaM可能是CCK_B受体的重要信号传递机制之一.     

μ- and μ4-η coordination of A2H2 (A = C, Si, Ge, Sn and Pb) ligands with transition metals

The heavier analogs of C₂H₂ have been studied at the B3LYP level for their μ and μ₄-η² coordination properties with the transition metals. Based on known alkyne compounds, transition metal fragments [W₂(μ-NH)(Cp)₂(Cl)₂] and [Fe₄(CO)₁₂] have been chosen. The SBKJC relativistic effective core potentials and their associated basis sets were used on W, Fe, Sn and Pb, and the 6-31G(d) basis set was used on all other elements. All the complexes of Si₂H₂, Ge₂H₂, Sn₂H₂ and Pb₂H₂ are found to be local minima. The trans-twist nature of the ligand A₂H₂ (A = Si-Pb) is large in μ-coordinated complexes of W, and it is very small in μ₄-η² coordinated complexes of Fe. The electronic structure of these complexes was investigated using fragment molecular orbital method (FMO).     

Interaction of Anions and Cations in Regulating Energy Distribution between the Two Photosystems

Cations such as Mg²⁺ regulate spillover of absorbed excitation energy mainly in favour of photosystem (PS) 2. Effect of low concentration (<10 mM) of the monovalent cation Na⁺ on chlorophyll (Chl) a fluorescence was completely overridden by divalent cation Mg²⁺ (5 mM). Based on Chl a fluorescence yield and 77 K emission measurements, we revealed the role and effectiveness of anions (Cl^-, SO₄ ^2-, PO₄ ^3-) in lowering the Mg²⁺-induced PS2 fluorescence. The higher the valency of the anion, the lesser was the expression of Mg²⁺ effect. Anions may thus overcome Mg²⁺ effects up to certain extent in a valency dependent manner, thereby diverting more energy to PS1 even in the presence of MgCl₂. They may do so by reversing Mg²⁺-induced changes.